1. Field of the Invention
This invention relates to a digital sundial (also referred to as a solar clock), and more particularly, to a digital sundial including one or more gnomon bodies, each comprising a plurality of stylus slits and segmented element openings for casting horological silhouettes.
2. Description of the Related Art
Sundial gnomons have employed a single stylus to cast sunlight or shadows onto a ruled dial or marked display surface, thereby showing the continuous passage of solar time. Modern improvements and refinements to sundials use gnomons comprising a plurality of styli to mark the passage of solar time.
U.S. Pat. No. 2,931,102 (Thew) shows a sundial with an arcuate band-like gnomon having perforations in the shape of horological marks, wherein the shadow of opaque or solid portions of the gnomon is cast onto a central shadow receiving area to display arabic symbols representing the hours of the day.
U.S. Pat. No. 4,387,999 (Shelley) discusses an electronic sundial apparatus having concentric hemispheres, each having a plurality of slits. The slits of the hemispheres function in conjunction to collimate sunlight once each hour at the concentric radial center of the hemispheres, where an electronic detector is located.
U.S. Pat. No. 4,782,472 (Hines) shows a solar clock with a digital time display. A cylindrical opaque mask member is provided with a series of sunlight-transmitting apertures which cooperate with a plurality of strategically positioned fiber optic arrays, coupled to a light-responsive digital display to provide a discrete indication of the solar time.
A digital sundial is shown in a pamphlet .COPYRGT. 1981 by Boon. The pamphlet states that slits "produce two inch high illuminated Roman numerals as the sun's rays pass over coded patterns of light and dark."
However, a need remains for a sundial gnomon to not only directly and precisely cast the sun's rays as digital numbers or horological silhouettes, but also to repetitively display horological symbols at successive periods to indicate common hourly intervals, such as the quarter hour or each ten minute interval thereof.